Genuine Toyota Parts for a 4AG 16V or 20V. 

• Front and rear main seals
• Front located behind the timing gear sprocket
• Rear located in front of flywheel.

Main seals will usually start to weep oil around 100K miles of use, or 10 years of age. We would certainly replace these if the flywheel is off for any reason, or if the lower timing belt cover is beginning to look oily. Oil on a belt can lead to valve train damage if the belt slips. This is cheap insurance.

Install with a light coat of Permatex grey on the outside, and a light coat of oil on the inside of the seal where moving parts will be in contact with the seal. Seal drivers and removers can be rented or loaned to you by your local auto parts store in most cases.